$128m upgrade doubles capacity at Pukekohe Wastewater Treatment Plant

Opening day at Pukekohe Treatment Plant

Our team and mana whenua are celebrating the completion of a $128m upgrade at the Pukekohe Wastewater Treatment Plant that doubles its capacity and improves water quality in the Parker Lane Stream.
Together with representatives of Waikato Tainui and Te Taniwha oo Waikato – a group representing nine marae along the lower Waikato River – our team marked the completion of the upgrade with a dawn blessing ceremony on site this morning.
The plant treats the wastewater from Pukekohe, Buckland, Tuakau, Pokeno and Patumahoe. The upgrades, which began in 2019 and have been completed this summer, double its capacity from 30,000 households to 60,000.
Board chair Margaret Devlin says the company has worked closely with mana whenua on this project since 2014.
“Seeing this project completed is a proud moment for us. The quality of the treated wastewater is so high it ultimately improves the water quality in Parker Lane Stream – a tributary of the Waikato River where the plant discharges to. And it caters for population growth in this rapidly growing area.”
We began conversations with mana whenua and other stakeholders about the need to renew the treatment plant’s wastewater discharge consent in 2014.

Dawn blessing
“Over the course of three years we explored the cultural, social and environmental concerns, while considering scientific data, engineering processes and cost implications.,” Devlin says.
“Our staff developed a new appreciation for the relationship mana whenua have with the awa, and the impact population growth had inflicted on it. We realised we needed not just to protect, but to restore the awa, and revised the design for the treatment plant to ensure it produced the highest-quality wastewater and improved water quality in the stream.”
Waikato Tainui executive chair Tukoroirangi Morgan says the plant’s extensive upgrade is a significant step in the right direction in addressing water quality in the Waikato River.
“Our position has always been the restoration of our taiao, especially our water sources which have sustained our tribal members for millennia.
“Conversations began in 2014 and while we are celebrating today, we would like more urgency applied to key infrastructure projects like this.
“The connections that have been made and maintained have opened the way for Watercare to engage directly with our people and we are confident that these relationships will endure.”
Franklin ward councillor Andy Baker says: “It’s great to see this important project completed. We’re expecting significant growth in Pukekohe over the next 30 years – the wastewater treatment plant’s upgrade enables the community to grow and the local economy to flourish.”
The upgrade was delivered in two stages, with the first breaking ground in May 2019.
Stage one involved the installation of new water inlet works, sludge and membrane reactors and a new UV light disinfection system. Electrical and chemical systems were also upgraded.
Stage two involved the conversion of the existing sequencing batch reactors to activated sludge reactors, which allowed the plant to double its capacity.
Wastewater operations controller Iris Tscharntke says the use of membrane bioreactors significantly lowers the level of nitrogen in the discharge.

Visiting the Pukekohe Treatment Plant
“Membrane bioreactors combine ultra-filtration – with spaghetti-like membranes that filter the wastewater – with biological treatment processes, where we have an army of good bugs eating the carbon in the liquid wastewater and reducing the amount of organic compounds and nitrogen. The Pukekohe Wastewater Treatment Plant is a state-of-the-art facility – one of the best domestic treatment plants in New Zealand.”